720's were sold both as a frameset and as a complete bike. Judging by the components you have on it now, yours was bought as a frameset. So I wouldn't worry about building it up as "original."

I had Suntour Superbe brakes on mine for many years. They fit 27" wheels admirably, but when I switched to 700c I had to get a Campy drop-center bolt for the rear brake; the Superbe caliper would not reach the 700c rim. The front was fine, though.

I'm not sure what the gray color of the brakes is, whether an anodized finish or a paint of some kind, but rest assured: removing it is easy. You'd want to disassemble the brakes completely and dunk the aluminum brake arms in the appropriate chemical, then polish with fine sandpaper and metal polish.